This invention relates to water soluble styrene-maleic anhydride ("SMA") resin arnic acids (amide-carboxylic acids) and to their use to prepare either (a) metallic pigment dispersions and metallic inks based thereon which are typically used for printing on paper and plastic substrates or as part of a decorative coatings formulation, or (b) organic pigment dispersions and water-based inks based thereon which are typically used for printing.
Since most polymeric surfactants currently used to prepare metallic pigment dispersions are salts of polycarboxylic acids, and have basic pHs, they give dispersions with poor stability and poor appearance due to tarnishing of the metallic pigment particles.
Similarly, current organic pigment dispersions are typically prepared using ammonium salts of styrene-acrylic acid polymers as the dispersing resin. These viscous dispersions have pigment loading and color limitations.
While SMA amic acids have been previously reported, they do not have the structure or water solubility of those of the instant invention. For example, Chem Abstract No. 117:213258 reports on a patent disclosure of the amic acid of SMA and cyclohexylamine, which composition would not be water-soluble.